1. Field of the Invention
The present invention relates to a dynamic fluid pressure bearing, a spindle motor, a disk drive apparatus and a method for manufacturing the dynamic fluid pressure bearing.
2. Description of the Related Art
A hard disk apparatus for use in a personal computer, a car navigation and so forth is equipped with a spindle motor arranged to rotate a magnetic disk about the central axis thereof. The spindle motor includes a configuration in which a stator and a rotor are rotated relative to each other with a bearing device arranged therebetween. In recent years, a fluid dynamic pressure bearing device is often used as a bearing device for the spindle motor. In the fluid dynamic pressure bearing device, a lubricant exists between a shaft and a sleeve. The shaft and the sleeve are rotated relative to each other in a state that they are supported by the dynamic fluid pressure of the lubricant.
Such a conventional fluid dynamic pressure bearing and a spindle motor provided with the same are disclosed in, e.g., Japanese Patent Laid-open Publication No. 2003-88042.
A hub for supporting disks, a thrust washer and the like are fixed to a shaft of the dynamic fluid pressure bearing. These members are fixed to the outer circumferential surface of the shaft.
The axial end surface of the hub, the thrust washer or the like is opposed to the axial end surface of a sleeve through the lubricant. For that reason, it is sometimes the case that a lubricating film with enhanced lubricating property is formed on the axial end surface of the hub or the like in order to improve the slidability between the hub or the like and the sleeve and also to protect the hub or the like and the sleeve from damage possibly caused when they make contact with each other.
If the end surface of the hub or the like having the lubricating film comes into contact with the shaft during the course of fixing the hub or the like to the shaft, however, there is a possibility that the lubricating film may be damaged and hence the hub or the like may be mounted to the shaft with reduced accuracy. In other words, the lubricating film is interposed between and deformed by the shaft and the lower surface of the hub or the like. Particularly, the amount of such deformation is unevenly distributed in a circumferential direction. This may lead to a possibility that the axial position of the hub or the like relative to the shaft is mismatched and the hub or the like may be slightly inclined with respect to the shaft.